The present disclosure relates to a driving apparatus, a driving method, and a program, and in particular, relates to a driving apparatus, a driving method, and a program which are able to, for example, drive an imaging element using an action mode which is desired by a user.
In recent years, from imaging elements (image sensors) which receive an optical image from a subject and generate an imaging image as an electric signal by being synchronized with a horizontal synchronization signal, demand to read out an imaging image with an arbitrary frame rate, number of lines, number of pixels, and read out speed is increasing.
Therefore, an adjustment technique exists for adjusting the frame rate when reading out an imaging image by changing the horizontal synchronization signal which is used to control the imaging element (for example, Japanese Unexamined Patent Application Publication No. 2007-135073).
Initially, a case where the frame rate is adjusted to 59.94 Hz using the adjustment technique described above will be described.
For example, as shown in FIG. 1, it is necessary that a first to a fourth condition below are satisfied in a case where the imaging image which is configured by 1080 lines is read out with a frame rate of 59.94 Hz.
As a first condition, it is necessary that a vertical synchronization period which represents an interval with regard to falling edges which are generated in the vertical synchronization signal, that is, one frame period which represents an interval where an imaging image is read out being 900900 (=54×106/59.94) clocks is satisfied. Here, the frequency of the clock is set at 54 MHz.
As a second condition, it is necessary that a horizontal synchronization period which represents an interval with regard to falling edges which are generated in a horizontal synchronization signal is set as a period of n clocks (for example 200 clocks) or more due to limiting A/D (analog/digital) conversion which is performed by the imaging element, a transfer rate when transferring the imaging image, or the like.
As a third condition, it is necessary that the vertical synchronization period and the horizontal synchronization period each represent a number of clocks which is an integer.
As a fourth condition, it is necessary that the number of horizontal synchronization periods in the vertical synchronization period is 1080, which is the number of lines which configure the imaging image, or more.
In this case, as shown in FIG. 1, if the horizontal synchronization signals where the horizontal synchronization period with 825 clocks are generated in only 1092 (=900900/825) periods in the vertical synchronization period, the first to the fourth conditions are satisfied and it is possible to adjust the frame rate to 59.94 (=54×106/900900) Hz.
Here, in the adjustment technique described above, as shown in FIG. 1, the frame rate is adjusted by changing the number of horizontal synchronization periods and the number of the clocks in the horizontal synchronization period due to providing a blanking period. This is the same in FIGS. 2 and 3 which will be described later.
Next, a case where the frame rate is adjusted to 239.76 Hz using the adjustment technique described above will be described.
For example, in a case where the frame rate is adjusted to 239.76 Hz (=4×59.94) which is four times 59.94 Hz, as a first condition, it is necessary that a vertical synchronization period being 225225 (=54×106/239.76) clocks is satisfied.
Accordingly, with the number of horizontal synchronization periods in the vertical synchronization period set as 1092, it is necessary that the horizontal synchronization period in one period is set as 206.25 (=54×106/(239.76×1092)) clocks in a case where the fourth condition is satisfied.
In this case, since the horizontal synchronization period is set as 206.25 clocks, the horizontal synchronization period satisfies the second condition of being 200 clocks or more but the third condition that both the vertical synchronization period and the horizontal synchronization period are a number of clocks which is an integer is not satisfied.
Therefore, when a combination where the third condition described above is satisfied is searched for, there are two combinations which are respectively shown in FIGS. 2 and 3.
That is, as shown in FIG. 2, there is a combination where the number of horizontal synchronization periods in the vertical synchronization period is set as 1155 and one period of the horizontal synchronization period is 195 clocks.
However, the combination satisfies the fourth condition that the number of horizontal synchronization periods in the vertical synchronization period is 1080 or more but the second condition that the horizontal synchronization period is 200 clocks or more is not satisfied.
In addition, as shown in FIG. 3, there is a combination where the number of horizontal synchronization periods in the vertical synchronization period is set as 1001 and one period of the horizontal synchronization period is 225 clocks.
However, the combination satisfies the second condition that the horizontal synchronization period is 200 clocks or more but the fourth condition that the number of horizontal synchronization periods in the vertical synchronization period is 1080 or more is not satisfied.